diff --git a/src/Pieces/PiecesFiles.cpp b/src/Pieces/PiecesFiles.cpp
index b6c70cd..15e7036 100644
--- a/src/Pieces/PiecesFiles.cpp
+++ b/src/Pieces/PiecesFiles.cpp
@@ -55,7 +55,12 @@ bool PiecesFiles::savePieces(int polyominoSize, std::vector<Polyomino>& polyomin
 
         // write the positions of the piece
         for (int i = 0; i < bytesNeeded; i++) {
-            buffer << static_cast<std::uint8_t>(polyomino.getPositionsData()[i/4] >> ((i%4) * 8));
+            buffer << static_cast<std::uint8_t>(
+                (
+                    polyomino.getPositionsData()[i / sizeof(std::uint64_t)] >> 
+                    (56 - ((i % sizeof(std::uint64_t)) * 8))
+                )
+            & 0xFF);
         }
     }
 
@@ -118,7 +123,8 @@ bool PiecesFiles::loadPieces(int polyominoSize, std::vector<Piece>& pieces, std:
 
         for (int j = 0; j < bytesNeeded; j++) {
             buffer >> positionByte;
-            polyominoData[j/4] |= static_cast<std::uint64_t>(positionByte) << ((j%4) * 8);
+            polyominoData[j / sizeof(std::uint64_t)] |= 
+                (static_cast<std::uint64_t>(positionByte) << (56 - ((j % sizeof(std::uint64_t)) * 8)));
         }
 
         pieces.emplace_back(Polyomino(std::move(polyominoData), length), pieceBlock);
diff --git a/src/Pieces/Polyomino.cpp b/src/Pieces/Polyomino.cpp
index 45d9e5d..f0e634a 100644
--- a/src/Pieces/Polyomino.cpp
+++ b/src/Pieces/Polyomino.cpp
@@ -277,7 +277,7 @@ std::vector<Position> Polyomino::getPositions() const {
             int posIndex = y * this->length + x;
             int longIndex = posIndex / (sizeof(std::uint64_t) * 8);
             int bitIndex = posIndex % (sizeof(std::uint64_t) * 8);
-            if (this->positions[longIndex] & static_cast<std::uint64_t>(1) << (sizeof(std::uint64_t) * 8 - bitIndex)) {
+            if (this->positions[longIndex] & static_cast<std::uint64_t>(1) << (sizeof(std::uint64_t) * 8 - bitIndex - 1)) {
                 result.push_back(Position(x, y));
             }
         }
@@ -328,19 +328,19 @@ bool Polyomino::contains(const Position& position) const {
     int posIndex = position.y * this->length + position.x;
     int longIndex = posIndex / (sizeof(std::uint64_t) * 8);
     int bitIndex = posIndex % (sizeof(std::uint64_t) * 8);
-    return this->positions[longIndex] & static_cast<std::uint64_t>(1) << (sizeof(std::uint64_t) * 8 - bitIndex);
+    return this->positions[longIndex] & static_cast<std::uint64_t>(1) << (sizeof(std::uint64_t) * 8 - bitIndex - 1);
 }
 
 void Polyomino::insert(const Position& position) {
     int posIndex = position.y * this->length + position.x;
     int longIndex = posIndex / (sizeof(std::uint64_t) * 8);
     int bitIndex = posIndex % (sizeof(std::uint64_t) * 8);
-    this->positions[longIndex] |= static_cast<std::uint64_t>(1) << (sizeof(std::uint64_t) * 8 - bitIndex);
+    this->positions[longIndex] |= static_cast<std::uint64_t>(1) << (sizeof(std::uint64_t) * 8 - bitIndex - 1);
 }
 
 void Polyomino::erase(const Position& position) {
     int posIndex = position.y * this->length + position.x;
     int longIndex = posIndex / (sizeof(std::uint64_t) * 8);
     int bitIndex = posIndex % (sizeof(std::uint64_t) * 8);
-    this->positions[longIndex] &= ~(static_cast<std::uint64_t>(1) << (sizeof(std::uint64_t) * 8 - bitIndex));
+    this->positions[longIndex] &= ~(static_cast<std::uint64_t>(1) << (sizeof(std::uint64_t) * 8 - bitIndex - 1));
 }
\ No newline at end of file